Microstructure evolution of SiO2, ZrO2-doped Y3Al5O12:Nd3+ ceramics obtained by reactive sintering

The evolution of microstructure, porosity and optical properties of SiO2, ZrO2-doped Y3Al5O12:Nd3+ laser ceramics obtained by reactive sintering have been studied. The relationship between the relative density and average grain size of garnet ceramics obtained in the 1500–1800 °С temperature range has been determined. It has been shown that anomalous behavior of sintering trajectory at Т>1700 °С may be due to the inhibition of ceramic grain boundaries mobility by Zr4+ ions. At the sintering temperature of 1800 °С a partial decomposition of Y3Al5O12:Nd3+, Si4+, Zr4+ solid solution occurs with precipitation of alumina along grain boundaries of ceramics. The relationships between the residual porosity, in-line optical transmittance and sintering conditions of Y3Al5O12:Nd3+ (4 at%) ceramics have been studied. Optical ceramics sintered at T=1750 °C for 12 h possess residual porosity of 0.0016 vol%, in-line optical transmittance of 82.9% at 1064 nm wavelength and laser slope efficiency of 33% under diode-pumping at 808 nm.